Israel, Iranian hardliners and US Congressional hawks warned last night that the world was about to seal a bad deal with Tehran, as foreign ministers scrambled to find a way of halting progress on Iran’s nuclear programme.

John Kerry, the US Secretary of State, broke off Middle East peace talks to fly to Geneva yesterday and was soon joined by William Hague, the Foreign Secretary and the French and German foreign ministers in what appeared to be a last-minute rush to reach agreement with the Iranian delegation.

Even signing a roadmap with Iran would represent an extraordinary breakthrough after almost